Question 1

Which choice best indicates the years of eruption for all of the premolars?

Accepted Answer

The first premolars erupt at 10-11 years of age. The second premolars erupt at 10-12 years of age with eruption of the maxillary teeth preceding the mandibular. This unique pattern is the most common exception to the rule that mandibular teeth erupt prior to their maxillary counterparts.

Question 2

Edentulous refers to

Accepted Answer

Edentulous means that all teeth are missing. A space maintainer is an appliance utilized to preserve space for either premature loss of a deciduous tooth or loss of any tooth. Unerupted third molars are considered impacted if they remain embedded in bone or soft tissue and fail to erupt.

Question 3

An impacted tooth is one that has

Accepted Answer

Impacted teeth are those that do not completely erupt but remain embedded in bone or soft tissue. There are varying degrees of impaction.

Question 4

The first deciduous teeth, the mandibular central incisors, erupt at approximately 6.5 to 7 months. The first permanent teeth, the maxillary premolars, erupt at approximately 6 years of age.

Accepted Answer

The first deciduous teeth are the mandibular central incisors, which erupt at approximately 6.5 to 7 months. Approximately 1 month later, the maxillary central incisors become visible. The first permanent teeth to erupt are the mandibular first molars, followed by the maxillary first molars within a few weeks. These teeth are often called the 6-year molars because they erupt at approximately 6 years of age. The maxillary premolars do not erupt until approximately 10-11 years of age.

Question 5

Which is the last permanent incisor to erupt?

Accepted Answer

The first general rule concerning eruption is that individual mandibular teeth precede their maxillary counterparts. Eruption of central incisors precedes eruption of lateral incisors. Thus, the maxillary lateral incisor is the last permanent incisor to erupt.

Question 6

Another name for the wearing away of the tooth through contact with an opposing tooth is

Accepted Answer

Attrition is the wearing away of a tooth through contact of its functioning surfaces with an opposing tooth. Exfoliation is the process by which the roots of primary teeth are dissolved and resorbed. Impaction is a term descriptive of teeth that do not completely erupt but remain embedded in bone or soft tissue. Resorption, as it applies to exfoliation of teeth, is a phenomenon caused by osteoclastic cells, which destroy the roots of deciduous teeth. Note that "clasts" are destructive cells whereas "blasts" are formative cells.

Question 7

A 6-year-old has a space maintainer on the area of the deciduous mandibular left first molar. Which permanent tooth will erupt in the space?

Accepted Answer

Deciduous molars are replaced by permanent premolars. The deciduous mandibular left first molar will be replaced by the permanent mandibular left first premolar. A space maintainer is an excellent device for preserving space in the event of premature loss of a deciduous tooth.

Question 8

Bicuspid is not an accurate name for premolars. Premolars can have two, three, or four cusps.

Accepted Answer

The term bicuspid is reserved for teeth that actually have two cusps. Premolars can have two or three cusps. Although patterns vary, in general the maxillary first and second premolars as well as the mandibular first premolars have two cusps. The mandibular second premolars can have two or three cusps.

Question 9

The most common exception to the rule of eruption that mandibular teeth precede eruption of maxillary teeth is the maxillary first premolar because this tooth often precedes eruption of its mandibular counterpart.

Accepted Answer

Eruption of the maxillary first premolar often precedes eruption of the mandibular first premolar. This is in direct contradiction to the first general rule of tooth eruption, which states that mandibular teeth usually precede the maxillary teeth.

Question 10

Which of the following selections include teeth that should be present in the dentition of a 3-year-old child (select all that apply)?

Accepted Answer

In a 3-year-old child all primary teeth should be present. Selections C and D are incorrect because they exclude primary teeth. Selection E is incorrect because the primary dentition does NOT have premolars. The primary dentition consists of twenty teeth comprised of incisors, canines, and molars.

Question 11

Small clumps of cells that will later form teeth are called

Accepted Answer

Tooth germs, which later form teeth, initially develop into growth centers and become developmental lobes. Ameloblasts are cells responsible for formation of enamel. Tubercles are cusp-like elevations.

Question 12

The rounded protuberances on the incisal edge of a newly erupted incisor are called

Accepted Answer

Mamelons, rounded protuberances on the incisal edge of a newly erupted incisor, are incisal ridges of the three labial developmental lobes. Regarding the incorrect selections, developmental grooves separate tooth lobes and are visible on erupted teeth as grooves separating cusps. Cusp tips are the most coronal and pointed aspect of a cusp. Tooth buds, also called tooth germs, are early cellular precursors to teeth. Attrition is the wearing away of tooth surface by contact with opposing tooth surfaces.

Question 13

Exfoliation is the process by which the roots of a deciduous tooth are pushed together by the calcification process. Resorption is the phenomenon where osteoblasts destroy the roots of primary teeth.

Accepted Answer

Exfoliation is the process by which the roots of a primary (deciduous) tooth are resorbed and dissolved until so little root remains that the primary tooth falls out. As a permanent tooth erupts, bone-destructive osteoclasts destroy the root of the deciduous tooth. This process is called resorption. Note that "clasts" are destructive cells whereas "blasts" are formative cells.

Question 14

Which of the following selections include teeth that should have erupted or may be in the process of eruption in the dentition of an 8-year-old child (select all that apply)?

Accepted Answer

The mixed dentition begins at about 6 years of age. The deciduous maxillary and mandibular central and lateral incisors will have been exfoliated in an 8-year-old child. At this age the central incisors of both arches should be present; the corresponding lateral incisors should be in the process of eruption. Permanent maxillary and mandibular first molars, appropriately called the 6-year molars, erupt at approximately 6 years of age. Permanent canines do not erupt until ages 9-12, with the mandibular canines preceding the maxillary.

Question 15

It is unusual for a 3-year-old child to have all twenty primary teeth because second molars do not typically erupt until 4 years of age.

Accepted Answer

The statement is incorrect because most children have all twenty primary teeth by the age of 3, and the reason is incorrect because second molars typically erupt by age 2-3, not 4.

Question 16

Roots of primary teeth resorb and dissolve because odontoblasts destroy the surrounding bone.

Accepted Answer

The initial statement accurately describes steps in the exfoliation of primary teeth. The reasoning provided is incorrect because odontoblasts are cells that form dentin. The cells that destroy surrounding bone during exfoliation of primary teeth are osteoclasts. Note that "blasts" are formative cells whereas "clasts" are destructive cells.

Question 17

A 15-month-old toddler would generally have (select all that apply):

Accepted Answer

By 15 months, a toddler typically has central incisors, lateral incisors, and first molars. Canines and second molars usually erupt later.

Question 18

Formation of teeth can be affected by nutritional deficiencies, fever, or childhood illnesses. While trauma to the dentition may delay eruption, it does not negatively impact formation of teeth.

Accepted Answer

Formation of teeth can be affected by many factors including nutritional deficiencies, fever, childhood illness, and trauma to the dentition. Not only may tooth formation by altered by these factors, formation or mineralization may be stopped completely.

Question 19

Maxillary molars have three major buccal cusps because the third buccal cusp develops from the lobe of Carabelli.

Accepted Answer

Maxillary molars have two major buccal cusps. The lobe, or cusp, of Carabelli is a small cusp-like elevation that develops into a tubercle. Most often seen on maxillary first molars, the cusp of Carabelli is considered a rudimentary lobe and is located on the lingual surface of the mesiolingual cusp.

Question 20

Permanent mandibular central incisors are the first succedaneous teeth to erupt. The earliest visible portion of an anterior tooth is the cusp of Carabelli, the name for the lingual lobe of mandibular central incisors.

Accepted Answer

Although the mandibular first molars are the first permanent teeth to erupt, they are NOT succedaneous because they do NOT replace primary teeth. It is important to remember that primary molars are replaced by permanent premolars. Therefore, the first succedaneous teeth to erupt are the permanent mandibular central incisors, which replace the primary mandibular central incisors. The cusp of Carabelli is a cusp-like elevation located on the maxillary first molar and occasionally on the maxillary second molar.

Quiz 5: Development, Form, and Eruption